A month after the events of The Box, Pinkie Pie's turn to the dark side and her epic battle with Gamma-Ray is faded from memory, and the box is seemingly lost forever. Things look bright for Rainbow and Pinkie as they rekindle their friendship. But hostile alien beings are on a mission to find Rainbow's box, and they won't let anypony stand in their way!

Little do they know, the box is in the hooves of the most unlikely pony in Equestria…